1. Field of the Invention:
This invention relates to apparatus for significantly reducing and, preferably, eliminating electrical arcing across electrical switch contacts as the switch is opened and, preferably, for significantly reducing the electrical arcing across the launch switch of an electromagnetic projectile launcher.
2. Description of the Prior Art:
Electromagnetic projectile launchers, generally, include a pair of electrically conductive rails which guide a projectile. The projectile is launched by quickly injecting, or commutating, an electrical current, from a high current source, into one of the rails. The electrical current then passes through the armature of the projectile and returns to the current source through the other rail. Acceleration of the projectile is produced by the interaction of the current through the armature of the projectile and the magnetic field which is produced by the same current flowing in the conductive rails.
The current which accelerates the projectile is initially shunted through a closed electrical switch which is connected in parallel with the armature of the projectile so that the current bypasses the armature of the projectile. The switch is not opened until a sufficient magnitude of current has developed. The switch is then rapidly opened, thereby quickly removing the parallel shunt to launch the projectile. Such opening of the electrical switch causes an arc across the terminals of the switch due to the combination of the large magnitude of current flowing through the switch and the impedance of the rail/projectile armature circuit. Such electrical arcing is undesirable since the energy discharged in the arc generates heat which destroys the contacts of the switch.